Fine adjustment means for incremental feed mechanisms

ABSTRACT

An incremental feed mechanism having a fine or incremental feed control wheel is connected in driving relationship with a drive transmitting hub which is rotatably mounted on a typewriter platen shaft. The hub is formed to provide an eccentric surface for rotatably supporting and transmitting rotary movement to a pair of integrally formed or connected axially spaced spur gears adapted to engage a first inner ring gear formed in a normally stationary line feed indexing ratchet and a second inner ring gear secured to a cylindrical typewriter platen, to thereby drive the cylindrical typewriter platen through minute and irregular arcs proportional to rotary movement of the incremental feed control wheel.

United States Patent [72] Inventor Ralph L. Parker 1,192,629 7/1916 l-lawley 197/114 Rockville, Conn. 1,433,920 10/1922 197/123 [21] Appl. No. 768,006 1,737,801 12/1929 197/114 [22] Filed Oct. 16, 1968 1,763,936 6/1930 Stickney 197/114 Patented May 11, 1971 Pnmary Exammer-Emest T. Wright, Jr. [73] Asslgnee i s gfifi i Att0rneys.loseph R. Spalla and Cornelius P. Quinn 54 FINE AD STMENT MEANS FOR IN REME 1 FEED MEJgHANISMS C NTAL ABSTRACT: An incremental feed mechanism having a fine or 5 C m incremental feed control wheel is connected in driving relationship with a drive transmitting hub which 18 rotatably I [52] US. Cl 197/114, mounted on a typewriter platen h ft The hub is fomed to 197/121, 1 97/187 provide an eccentric surface for rotatably supporting and [51 1 Int. rotary movement to a pair of formed or 0f 14, connected paced pur gears adapted to engage a I22, 189 inner ring gear formed in a normally stationary line feed indexing ratchet and a second inner ring gear secured to a cylin- [56] References cued drical typewriter platen, to thereby drive the cylindrical UNITED STATES PATENTS typewriter platen through minute and irregular arcs propor- 717,l49 12/1902 Webb 197/ 121 tional to rotary movement of the incremental feed control 1,056,703 3/1913 Lux 197/ 123 wheel.

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- sum Inf 2 INVENTOR RALPH L. PARKER TTORNEY PATENT EUHAYHIQYI 3,578,134

' SHEEIZUFZ la I INVENTOR 22 29a 30 RALPHLDPARKER 2 [-19.4- BY 4% W v ATTORNEY FINE ADJUSTMENT MEANS FOR INCREMENTAL FEED MECHANISMS BACKGROUND OF THE INVENTION This invention relates to an incremental feed mechanism for incrementally rotating the cylindrical platen of a typewriter; and more particularly to an incremental feed mechanism employing a positive drive for rotating the cylindrical platen of a typewriter through minute and irregular arcs.

In typewriters, a line feed indexing ratchet is normally employed to rotate a cylindrical typewriter platen through preselected uniform arcs and is provided with a detent means for normally holding the line feed indexing ratchet biased against rotation. In addition to having a line feed indexing ratchet for rotating the cylindrical typewriter platen through preselected uniform arcs, it is also customary to provide means for rotatably adjusting the platen in finer increments than can be obtained from the line feed indexing ratchet so that an operator after inserting paper about the cylindrical platen may bring a ruled line or any desired point on the paper into register with a printing point, thereby facilitating the work of typewriting upon ruled paper and blank forms, as well as the correction of errors.

Prior ro the present invention, known mechanisms provided for rotatably adjusting a platen in finer increments than that obtainable from a line feed indexing ratchet often included a friction drive and necessitated the releasing of a clutch, a lock, a friction gear, or the like ,to disengage the line feed indexing ratchet from the platen. The principal disadvantage of each of these prior mechanisms was the difficulty of accurately rotatably adjusting the platen through minute and irregular arcs. In mechanisms employing frictional engaging surfaces there existed the ever present problems of slippage, while in mechanisms involving theengagement and disengagement of gear teeth, not only was the degree of rotatable adjustment of the platen limited by the size of the gear teeth, but when fine gear teeth were employed, since the alignment of the teeth was extremely critical, they were often subject to damage during reengagement.

SUMMARY OF THE DISCLOSURE The incremental feed mechanism of the present invention avoids the problems inherent in prior art devices by providing an efficient, positive and direct mechanical drive from an in-,

cremntal feed control wheel to a typewriter platen. A hub projecting axially from the incremental feed control wheel is rotatably mounted on a platen shaft and provides an eccentric surface for rotatably mounting a pair of integrally connected axially spaced spur gears. One of the spur gears is adapted to engage a first inner ring formed in a detented line feed indexing ratchet, and the other spur gear is adapted to engage a second inner ring gear secured to the platen, so that with the line feed index wheel prevented from rotating, rotational movement imparted to the incremental feed control wheel is translated into movement of the platen.

Accordingly, it is an object of the present invention to provide a new and improved direct positive drive for incrementally rotating a typewriter platen through minute and irregular arcs independently of a line feed indexing ratchet.

Another object of the present invention is to provide a mechanism for rotatably moving a cylindrical typewriter platen through minute and irregular arcs, without the need of employing a clutch or laterally moving a gear to disconnect the platen from the line feed indexing ratchet.

Still another object of the present invention is to provide a mechanism for directly rotating a cylindrical typewriter platen through any are independently of the line feed indexing ratchet.

Afurther object of the present invention is to provide auxiliary mechanically powered drive means for continuously rotating a cylindrical typewriter platen to provide rapid insertion or ejection of paper about the platen.

A still further object of the present invention is to provide a mechanism for rotatably moving a typewriter platen through minute and irregular arcs wherein play normally inherent in such a mechanism is automatically eliminated.

Other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following description of the invention taken in conjunction with the drawing, which forms a part thereof.

In the drawing:

FIG. I is a top sectional view of the platen feed mechanism of the present invention;

FIG. 2 is a side view of a section of a line feed indexing ratchet illustrated in FIG. 1, with a check or detent roller;

FIG. 3 is a sectional view of the platen feed mechanism taken along lines 3-3 of FIG. 1, with a platen section broken away to show a second eccentrically mounted spur gear in engagement with a second inner ring gear secured to the platen and a first eccentrically mounted spur gear, integrally connected with the second eccentrically mounted spur gear, in engagement with a first inner ring gear formed in the line feed indexing ratchet;

FIG. 4 is a sectional view similar to FIG. 1 showing an alternate embodiment of the platen feed mechanism employing beveled spur gears and beveled inner ring gears in conjunction with a biasing means to insure a tight fit between the gears and the elimination of play;

FIG. Sis a side view partly in section showing the present invention in combination with a mechanical drive for providing rapid insertion and ejection of paper about the platen; and

FIG. 6 is a top view of the incremental feedcontrol wheel illustrated in FIGS. 1, 2 and 4 in conjunction with a reference pointer mounted on the typewriter frame or carriage.

DESCRIPTION OF THE INVENTION Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is illustrated in FIG. '1 a cylindrical rubber covered platen, generally identified by the reference numeral 10, provided with centrally bored circular end plates, 11 and 12 respectively, through which a platen shaft 13 extends, whereby'the platen 10 is axially supported and held against rotation relative thereto by a set screw 9. The shaft 13 is joumaled in a typewriter or carriage frame 14, as the case may be, and is provided at its projecting ends with control knobs IS, fixed upon the shaft 13 by set screws 16, for manually rotating the cylindrical platen l0.

Immediately to the right of the left side frame 14, as shown in FIG. 1, a fine or incremental feed control knob or wheel 17 for manually rotating the platen 10 through minute and irregular arcs, as will hereinafter be described, is keyed to a drive transmitting hub 19 rotatably mounted on the platen shaft 13 by a pin 18 received within a radial hole 18a bored into wheel 17 and extending into an axial slot in hub 19. The drive transmitting hub 19, from left to right as viewed in FIG. 1, has a concentric surface 19a and an eccentric surface 1%. The concentric surface 19a of the hub 19 rotatably supports a line feed indexing ratchet wheel 21 and the eccentric surface 19b which is greater in circumference than the concentric surface 19a, rotatably supports a pair of integrally formed axially spaced first and second spur gears 26 and 27 thereon. The first and larger spur gear 26 and the second spur gear 27 may vary in size and number of teeth to produce a desired stepdown ratio between rotary movement of the incremental feed control wheel 17 and the cylindrical platen 10.

As illustrated in-FIG. 2, ratchet teeth 22 are formed on the periphery of the line feed indexing ratchet 21 for cooperation with a pawl (not shown) adapted to rotate the line feed indexing ratchet wheel 21, and the cylindrical platen 10 through preselected uniform arcs. Detent means are also provided for engagement with the ratchet teeth 22 to prevent inadvertent rotation of the line feed indexing ratchet 21. The detent means for preventing inadvertent rotation of the line feed indexing ratchet 21 comprises a check or detent roller 23 carried by the free end of one of the angularly disposed arms of a bell crank 24 pivotally mounted on a stud 24a projecting from the typewriter or carriage frame 14 and biased into engagement with the ratchet teeth 22 by a spring 25 connected to the other angularly disposed arm of the bell crank 24,

As most clearly shown in FIG. 3, the first spur gear 26 engages a first inner ring gear 28 formed in a rightwardly extending annular portion of the line feed indexing ratchet wheel 21, and the second spur gear 27 engages a second inner ring gear secured by pins 30 to the end plate 11 of the cylindrical platen 10.

When the ratchet wheel 21 is rotated, its ring gear 28 drives spur gear 26 together with integral spur gear 27 about their own centers i.e., around circular surface 191) of hub 19, and spur gear 27 in turn drives the platen ring gear 29 secured to the platen moving it in the same direction as the ratchet wheel 21. Similarly, as the platen knobs 15 are connected by set screws 16 to platen shaft 13 which is in turn connected to the platen by a set screw 9, rotation of a platen knob rotates the platen 10. This platen rotation via platen knobs 15 via platen ring gear 29 drives spur gear 27 together with spur gear 26 about their centers and spur gear 26 in turn drives the ratchet wheel 21.

With the line feed indexing ratchet wheel 21 held stationary by the detent or check roller 23, rotation of the incremental feed control wheel 17 is transmitted to the cylindrical platen 10 through the action of the eccentric surface 19b of the hub 19, the first and second spur gears 26 and 27 and the first and second inner ring gears 28 and 29, thereby producing relative movement between the cylindrical platen 10 and the incremental feed control wheel 17 in proportion to the gear ratio between the first and second spur gears 26 and 27.

More particularly, as the incremental feed control wheel 17 is rotated its movement is transmitted to the first and second spur gears 26 and 27 by the eccentric surface 19b of the hub 19. Since the line feed indexing ratchet 21 is held stationary, the first spur gear 26 is unable to force the first inner ring gear 28 formed in the line feed indexing ratchet 21 to revolve. Accordingly, the first spur gear 26 revolves about its own center around the eccentric surface 19b of the drive transmitting hub 19 and travels around the first inner ring gear 28 about the center of hub 1%. This gear 28 may be regarded as a temporarily fixed circular rack and in effect the driver of the first spur gear 26. Thus, the second spur gear 27 integrally fomied with the first spur gear 26 also rotates around its own center and in so doing, because of the differences in the number of teeth in gears 28 and 29, drives the second inner ring gear 29 secured to the end plate 11 of the cylindrical platen 10, moving the cylindrical platen 10 through an angle directly proportional to and in the opposite direction as the angular movement of the incremental feed control wheel 17.

By varying the relative size and the number of teeth on the' first and second'spur gears 26 and 27, any desired ratio of movement between the incremental feed control wheel 17 and the cylindrical platen 10 may be established.

In another embodiment of the invention as illustrated in FIG. 4, means are provided to eliminate end and radial play between the incremental feed control wheel 17 and the platen 10. In this embodiment of the invention, beveled first and second inner ring gears 28a and 29a replace the first and second inner ring gears 28 and 29 illustrated in FIGS. 1 and 3, and the first and second spur gears 26 and 27 illustrated in FIGS. 1 and 3 are replaced by beveled first and second spur gears 26a and 270. A compressed spring 30 telescoping an axially extending annular portion 31 of the line feed indexing ratchet 21, abuts a shoulder 32 on the line feed indexing ratchet 21 and a face 33 of the incremental feed control wheel 17 to bias the line feed indexing ratchet 21 to the right as seen in FIG. 4 so that the beveled first inner ring gear 280 formed in the line feed indexing ratchet 21 applies pressure against the beveled first spur gear 26a urging the beveled second spur gear 27a integrally connected to the beveled first spur gear 26a, into tight contact with the beveled second inner ring gear 29a, thereby eliminating end and radial play between the incremental feed control wheel 17 and the cylindrical platen 10.

Referring now to FIG. 5, an auxiliary mechanical drive may be provided in conjunction with either of the incremental feed mechanisms described above and illustrated in FIGS. 1--4 to provide rapid insertion or ejection of paper about the platen 10. While this mechanism is particularly suited to typewriters in which there is no lateral movement of the typewriter platen, such a mechanism may also be employed in a typewriter having a laterally movable platen.

As shown in FIG. 5, a continuously rotating pulley 40 rigidly mounted on a rotating shaft 41 drives a belt 42 and pulley 43 about a hub '45 eccentrically mounted on a stud 44 extending from a typewriter or carriage frame 14. A lever 46 rigidly mounted on the hub 45 as by a screw 46a is biased in a counterclockwise direction by a spring 47 into abutment with a stop 48 mounted on a typewriter or carriage frame 14 and is adapted when moved in a clockwise direction to place the pulley 43 driven by the belt 42, or the belt 42 itself, into frictional engagement with the peripheral surface of the incremental feed control wheel 17 so as to rapidly rotate the cylindrical platen 10 and thereby insert paper thereon or eject paper therefrom.

As illustrated in FIG. 6, if desired, a reference pointer 51 may be mounted on the typewriter or carriage frame 14 and calibrated divisional lines may be provided on the periphery of the incremental feed control wheel 17 to assist the operator in adjusting the cylindrical platen 10 to a desired position, and afterwards, if the operator so desires, assist in returning the cylindrical platen 10 to its original position. The division lines are so calibrated that the distance between major divisional lines 52 is equivalent to the angular distance traveled by one increment of the line feed indexing ratchet 21.

Thus, an efficient drive feed control mechanism possessing a positive mechanical drive for accurately rotatably moving a cylindrical typewriter platen through any minute and irregular arcs desired is provided by eliminating the disadvantages inherent in mechanisms of the prior art intended for this pur' pose.

I claim:

1. In a typewriter having a frame,

a shaft rotatably supported on said frame,

aplaten secured to said shaft,

a line feed indexing ratchet wheel rotatably indexable through preset increments,

a detent roller for normally holding said ratchet wheel biased against rotation,

an incrementally rotatable feed control wheel,

and mechanism for coupling said ratchet wheel and said control wheel respectively to drive said platen through increments corresponding to those through which said ratchet wheel is rotated, and to drive said platen relative to said ratchet wheel through increments proportional to those through which said control wheel is rotated,

said mechanism comprising,

a first inner ring gear formed internally of said ratchet wheel,

a second inner ring gear secured to said platen adjacent said first ring gear,

integrally formed first and second spur gears meshing with said first and second ring gears,

and a drive transmitting hub rotatably mounted on said platen shaft secured to said control wheel having a concentric portion rotatably supporting said ratchet wheel and an eccentric portion rotatably supporting said spur gears,

2. A typewriter platen feed mechanism as recited in claim 1, wherein the gear teeth of said first inner ring gear, said second inner ring gear, and said first and second spur gears are beveled.

3. A typewriter platen feed mechanism as recited in claim 2, further comprising resilient means urging lateral movement of calibrated divisional lines provided on the periphery of the incrementally rotatable feed control wheel and a reference pointer associated with said calibrated divisional lines mounted on the typewriter frame.

5. A typewriter platen feed mechanism as recited in claim 4 further comprising auxiliary power means for selectively frictionally engaging incrementally rotatable feed control wheel to power drive the incrementally rotatable feed control wheel and thereby insert paper about the shaft supported platen and eject paper from about the shaft supported platen. 

1. In a typewriter having a frame, a shaft rotatably supported on said frame, a platen secured to said shaft, a line feed indexing ratchet wheel rotatably indexable through preset increments, a detent roller for normally holding said ratchet wheel biased against rotation, an incrementally rotatable feed control wheel, and mechanism for coupling said ratchet wheel and said control wheel respectively to drive said platen through increments corresponding to those through which said ratchet wheel is rotated, and to drive said platen relative to said ratchet wheel through increments proportional to those through which said control wheel is rotated, said mechanism comprising, a first inner ring gear formed internally of said ratchet wheel, a second inner ring gear secured to said platen adjacent said first ring gear, integrally formed first and second spur gears meshing with said first and second ring gears, and a drive transmitting hub rotatably mounted on said platen shaft secured to said control wheel having a concentric portion rotatably supporting said ratchet wheel and an eccentric portion rotatably supporting said spur gears,
 2. A typewriter platen feed mechanism as recited in claim 1, wherein the gear teeth of said first inner ring gear, said second inner ring gear, and said first and second spur gears are beveled.
 3. A typewriter platen feed mechanism as recited in claim 2, further comprising resilient means urging lateral movement of the line feed indexing ratchet wheel and said integrally formed first and second spur gears toward said second inner ring gear, thereby providing said first inner ring gear and said second inner ring gear a tight fit with said first and second spur gears and the elimination of play therebetween.
 4. A typewriter feed mechanism as recited in claim 3, further comprising, indicator means for measuring the angular movement of the platen relative to the line feed indexing ratchet effected by movement of the incrementally rotatable feed control wheel, said indicator means including a plurality of calibrated divisional lines provided on the periphery of the incrementally rotatable feed control wheel and a reference pointer associated with said calibrated divisional lines mounted on the typewriter frame.
 5. A typewriter platen feed mechanism as recited in claim 4 further comprising auxiliary power means for selectively frictionally engaging incrementally rotatable feed control wheel to power drive the incrementally rotatable feed control wheel and thereby insert paper about the shaft supported platen and eject paper from about the shaft supported platen. 